On the facile dehydrohalogenation of amino acid derived chloromethyl ketones.

Amino acid derived chloromethyl ketones are shown to undergo a general dehydrohalogenation reaction under mild, basic, nonnucleophilic conditions to afford α-β-unsaturated ketones.     

Maxwell's Demon and detailed balancing

A particle of molecular dimensions which can exist in two states is associated with a membrane pore through which molecules of a gas can pass. The gas molecules from two identical phases on either side of the membrane may pass only when the particle is in one particular state. If certain restrictions are imposed on the system, then the particle appears to act like a Maxwell's Demon⁽¹⁾ which “handles” the gas molecules during their passage through the pore.     

Cauchy and the infinitely small

We consider Cauchy's use of the infinitely small in his textbooks. He never examined fully his concept of variables with limit zero, and he sometimes argued as if he were using actual infinitesimals. Occasionally he adopted an epsilon-delta approach. The author argues that historical evaluations of mathematical analysis may and should be made in the light of both standard and non-standard analysis. From this point of view, Cauchy's move toward founding analysis entirely on the standard real number system does not seem to have been inevitable. Some historical observations by the founder of non-standard analysis, Abraham Robinson, are extended, and in one case contested. It is shown that some of Cauchy's alleged errors are explained if he is admitted to have been thinking of actual infinitesimals and infinitely large integers. Cauchy's definitions of differential in his textbooks are examined, and the author shows that the earlier of his two definitions of total differential works well, but the later does not.     

On stationary baroclinic planetary dipole-vortices in a continuously-stratified fluid of finite depth

It is qualitatively known that the gravest mode associated with a vertical normal-mode decomposition of a stationary, baroclinic modon in a continuously-stratified fluid of finite depth on a -plane necessarily contains an exterior downstream Rossby wave field if the background zonal flow is eastward. An. exact solution is presented describing this situation which satisfies the correct upstream no-waves constraint.     

Actinophyllic acid, a potent indole alkaloid inhibitor of the coupled enzyme assay carboxypeptidase u/hippuricase from the leaves of Alstonia actinophylla (Apocynaceae)

Bioassay-guided fractionation of the aqueous extract of the leaves of Alstonia actinophylla with use of a coupled enzyme assay, CPU/hippuricase, to detect carboxypeptidase U inhibitors led to the isolation of a novel indole alkaloid, actinophyllic acid (1). The structure of 1 was determined from detailed 2D NMR studies. Actinophyllic acid was found to be a potent inhibitor of the coupled enzyme assay with an IC(50) of 0.84 microM. Actinophyllic acid possesses a unique 2,3,6,7,9,13c-hexahydro-1H-1,7,8-(methanetriyloxymethano)pyrrolo[1',2':1,2]azocino[4,3-b]indole-8(5H)-carboxylic acid skeleton.     

Conformational analysis by scaled energy embedding

Distance geometry has been used for some years to find conformations of molecules consistent with given bounds on the interatomic distances. A recent extension of the method, called energy embedding, enforces the geometric constraints as before, but also biases the results toward low-energy structures. Now a significant improvement on energy embedding is presented, which is less dependent on local optimization for satisfying the geometric constraints. Tests on very small systems with well understood energy functions show that the global minimum energy value is often attained, and geometric constraints are always satisfied.     

Nickel(II) and copper(II) complexes of 5-substituted-salicylaldehyde thiosemicarbazones

Binuclear nickel(II) and copper(II) complexes with four 5-methoxysalicylaldehyde N(3)-substituted thiosemicarbazones and nickel(II) complexes of four 5-nitro-salicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic, and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H- and 13C-n.m.r spectra of the thiosemicarbazones, have been obtained. None of these compounds show significant growth inhibitory activity against the fungi Aspergillus niger and Paecilomyces variotii.